In the context of the present invention the term “hearing device” refers to hearing aids (alternatively called hearing instruments or hearing prostheses) used to compensate hearing impairments of hard of hearing persons as well as to audio and communication devices used to provide sound signals to persons with normal hearing capability, e.g. in order to improve hearing in harsh acoustic surroundings. Such hearing devices are able to process a received input sound signal and then provide the processed sound signal to the user, e.g. into his ear canal. The processing is for instance automatically adapted to the prevailing listening situation. Furthermore, the hearing device settings are adjusted according to the individual preferences and needs of the user, for instance in dependence of the user's specific hearing capability/deficiency, e.g. hearing loss. The process of adjusting hearing device settings, such as hearing programs or signal processing parameters, for a specific user is commonly referred to as fitting and is usually performed by a trained fitter such as a hearing device or hearing healthcare professional, e.g. an audiologist, ENT doctor, or a hearing device dispenser, at his office.
As indicated above, hearing devices can be used for a variety of purposes such as to compensate hearing impairments of hard of hearing persons or to improve the hearing for persons with normal hearing capability in harsh acoustic surroundings. Most of these hearing devices are worn at a user's ear or at least partly within the user's ear canal. The user will in fact typically employ a pair of hearing devices worn at or in both ears in order to improve their effectiveness. Whatever the intended use, it will often be beneficial for a single user to employ a plurality of hearing devices (akin to using separate pairs of corrective lenses for different purposes, e.g. for reading and driving as well as utilising sunglasses and safety glasses in order to protect the eyes against bright light and shield them from hazardous debris), e.g. a second (pair of) hearing device(s) with a different acoustic coupling (i.e. acoustically open vs. sealed), a spare (pair of) hearing device(s) for use during repair or charging or in case of theft or loss of the other (pair of) hearing device(s), an extra (pair of) hearing device(s) for use as remote microphone(s), a second (pair of) hearing devices for use under adverse conditions (e.g. for swimming, high humidity, dirty environments), a second (pair of) cosmetically appealing hearing device(s) (while the first (pair) is bulky but is capable of providing a higher sound output power level). Such an extra/second (pair of) hearing device(s) could be provided to the user at a reduced price as a gratification for “brand loyalty” or as a reward for recruiting a new user/customer. In all these cases, the second (pair of) hearing device(s) will generally be sold at a lower price to an existing user/customer. However, the hearing device manufacturer or supplier will want to make sure that the salesperson, e.g. the hearing device dispenser or audiologist is unable to sell the cheaper second (pair of) hearing device(s) to another customer/user at the full price charged for the first (pair) of hearing device(s). Hence, there exists a need to provide means for solving this problem when supplying a set of “associated” or “companion” hearing devices, whereby two or more “associated” or “companion” hearing devices are intended to be employed by the same user at different times (i.e. not simultaneously, as in the case of a binaural fitting for both ears) and for instance for different purposes and/or in different situations.